In the description of Japanese Unexamined Patent Publication No. 2003-042199, “in order to exert the function of a parking brake without spoiling the function of an electric brake”, “a pawl wheel is disposed on a peripheral surface of a rotor of a motor. An engagement pawl biased in one direction with a torsion spring is disposed on an oscillating arm disposed around the rotor. The oscillating arm is always biased toward the pawl wheel with a tension spring. In this description, braking force is generated with rotation in a braking direction of the rotor in the operation of the parking brake. Thereafter, electric conduction to the motor is cut off to cause engagement between the engagement pawl and the pawl wheel to regulate returning of the rotor”. In the description, “when the parking brake is operated, the engagement pawl keeps a projecting attitude to be brought into contact with a projection with biasing force of the torsion spring. As a result, the engagement of the engagement pawl and the pawl wheel regulates counterclockwise rotation of the rotor to establish the parking brake (see FIG. 3 in Japanese Unexamined Patent Publication No. 2003-042199).
The parking brake mechanism described in Japanese Unexamined Patent Publication No. 2003-042199 uses an oscillating arm (Lever) to interlock the pawl member with a ratchet wheel. However, a structure (direct drive structure) in which a solenoid actuator (to also be simply referred to as a solenoid) directly drives the pawl member to miniaturize the device is strongly desired. The direct drive structure requires that “relative location accuracy between the ratchet wheel and the pawl member is secured”, consequently, that “the ratchet wheel and the pawl member are reliably interlocked with each other when the solenoid is turned on”